PERFORMANCE OF 2 EUCALYPTUS SPECIES AT DIFFERENT SLOPE POSITIONS AND ASPECTS IN A CONTOUR-RIDGE PLANTING SYSTEM IN THE NEGEV DESERT OF ISRAEL

The growth of Eucalyptus occidentalis and Eucalyptus sargentii, establ ished in January 1987 at different slope positions and aspects under a water-harvesting system in Dudaim, Negev Desert of Israel, was invest igated during October 1991 to January 1992 and September-December 1993 , Seven years after planting, E. sargentii had higher above-ground bio mass (AGE) than E. occidentalis (91.17 +/- 3.99 kg vs. 45.82 +/- 2.00 kg per tree) and had 70% foliage biomass as opposed to 40% in E. occid entalis. The two species did not differ significantly in their stem bi omass (SB) and total height (H). The effect of slope position on tree growth was significant; trees in the mid-slope position (with shallowe r soils of high sodicity) showed the lowest AGE and SB yield (30% less than those of the other positions) and lower height. The effect of as pect on tree growth was also highly significant. In general, trees on northern aspects had higher SB and AGB and H, than those on western as pects; trees on southern aspects were the poorest in growth. The study suggests that E. sargentii is a better shade and windbreak tree, whil e E. occidentalis is a better fuelwood species under arid-zone conditi ons.